1,347 research outputs found

    NonLocal Systems of Balance Laws in Several Space Dimensions with Applications to Laser Technolog

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    For a class of systems of nonlinear and nonlocal balance laws in several space dimensions, we prove the local in time existence of solutions and their continuous dependence on the initial datum. The choice of this class is motivated by a new model devoted to the description of a metal plate being cut by a laser beam. Using realistic parameters, solutions to this model obtained through numerical integrations meet qualitative properties of real cuts. Moreover, the class of equations considered comprises a model describing the dynamics of solid particles along a conveyor belt

    Smooth and discontinuous junctions in the p-system

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    Consider the p-system describing the subsonic flow of a fluid in a pipe with section a = a(x). We prove that the resulting Cauchy problem generates a Lipschitz semigroup, provided the total variation of the initial datum and the oscillation of a are small. An explicit estimate on the bound of the total variation of a is provided, showing that at lower fluid speeds, higher total variations of a are acceptable. An example shows that the bound on TV(a) is mandatory, for otherwise the total variation of the solution may grow arbitrarily.Comment: 27 pages, 4 figure

    Coupling conditions for the 3x3 Euler system

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    This paper is devoted to the extension to the full 3×33\times3 Euler system of the basic analytical properties of the equations governing a fluid flowing in a duct with varying section. First, we consider the Cauchy problem for a pipeline consisting of 2 ducts joined at a junction. Then, this result is extended to more complex pipes. A key assumption in these theorems is the boundedness of the total variation of the pipe's section. We provide explicit examples to show that this bound is necessary.Comment: 21 pages, 6 figure

    Stemarane diterpenes and diterpenoids

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    In this article the scientific activity carried out on stemarane diterpenes and diterpenoids, isolated over the world from various natural sources, was reviewed. The structure elucidation of stemarane diterpenes and diterpenoids was reported, in addition to their biogenesis and biosynthesis. Stemarane diterpenes and diterpenoids biotransformations and biological activity was also taken into account. Finally the work leading to the synthesis and enantiosynthesis of stemarane diterpenes and diterpenoids was described

    Effect of biofilm removal from the occlusal tooth surfaces on fluorescence measurements. A clinical study

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    Aim: Early diagnosis and monitoring of caries lesions are the most important issues of primary and secondary prevention policies.The intraoral VistaCamiX(DurrDental, Bietigheim‐Bissingen,Germany) uses the fluorescence phenomenon for a non‐invasive, quantitative caries diagnosis. In order to make a precise evaluation the tooth surface must be completely cleaned and without biofilm. The current study aimed to evaluate the effects of biofilm removal, using air‐polishing device (Combi,MectronSpA) with glycine, on fluorescence VistaCam iX camera quantitative measurements of caries. Methods: Patients with complete permanent dentition without any kind of restorative treatments in the lateral and posterior section of upper and lower dental arches were enrolled. The occlusal surfaces of molars and premolars were photographed using the fluorescence terminal Proof of the intraoral camera VistaCam iX before and after air polishing glycine procedures, registering the highest value gained for each occlusal surface. Results:133cuspidate permanent teeth of patients aged between 13 and 25 were analyzed. Descriptive analysis showed an average of 0.82 (SD=0.65; Min=0.00; Max=1.80; Median=1.20) and of 0.93 (SD=0.60; Min=0.00; Max=1.70; Median=1.20) for values before and after treatment, respectively.The scores assigned by VistaCam iX Proof fluorescence based camera to the occlusal surfaces, after the air‐polishing treatment, are averagely higher than those before treatment, especially in the diagnosis of initial tooth decay. Conclusion: Biofilm removal with glycine air‐polishing improves the VistaCam camera accuracy in recognizing healthy tissue from the decayed one, due to the fact that air-polishing treatment increases the decayed tissue reaction to the fluorescence

    Novel locally active estrogens accelerate cutaneous wound healing-part 2

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    Estrogen deprivation is associated with delayed healing, while estrogen replacement therapy (ERT) accelerates acute wound healing and protects against development of chronic wounds. However, current estrogenic molecules have undesired systemic effects, thus the aim of our studies is to generate new molecules for topic administration that are devoid of systemic effects. Following a preliminary study, the new 17ÎČ-estradiol derivatives 1 were synthesized. The estrogenic activity of these novel compounds was evaluated in vitro using the cell line ERE-Luc B17 stably transfected with an ERE-Luc reporter. Among the 17ÎČ-estradiol derivatives synthesized, compounds 1e and 1f showed the highest transactivation potency and were therefore selected for the study of their systemic estrogenic activity. The study of these compounds in the ERE-Luc mouse model demonstrated that both compounds lack systemic effects when administered in the wound area. Furthermore, wound-healing experiments showed that 1e displays a significant regenerative and anti-inflammatory activity. It is therefore confirmed that this class of compounds are suitable for topical administration and have a clear beneficial effect on wound healing

    Implementing post-orthodontic compliance among adolescents wearing removable retainers through Whatsapp: a pilot study

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    Purpose: To determine whether the use of social media is useful in improving compliance and follow-up attendance among patients wearing retainers after orthodontic treatment. Patients and methods: Sixty post-orthodontic patients (aged 16-19 years), randomized in two groups: follow-up supported by participation in WhatsApp chat group (SG), and Control Group (CG). All patients were scheduled for quarterly check-ups for monitoring of orthodontic stability by measurement of intercanine width at the beginning of the study (t(0)) and every 4 months t(1), t(2), t(3)) for 1 year of observation. Patients in the SG additionally participated in a WhatsApp chat group, where they would send, on a weekly basis, snapshots showing his/her occlusion. Every month, the orthodontist acting as the moderator awarded the best five snapshots by publishing a ranking in the chat. Results: Participants in the SG featured smaller changes from the intercanine widths at baseline (at debonding) compared to the CG patients at all times during 1 year of follow-up. Follow-up attendance was regular in both groups in the first 8 months of follow-up. After that, patient compliance decreased in the CG, with eight patients missing check-up appointments. Conclusion: Engaging adolescent patients directly through WhatsApp activity seems to increase regularity in wearing removable retainers, attendance to follow-up schedule, and yield better long-term outcome in terms of orthodontic stability and compliance

    Optical discrimination between malignant and benign breast lesions

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    Time domain multi-wavelength (635 to 1060 nm) optical mammography was performed on 82 subjects with breast lesions (45 malignant and 38 benign lesions). A perturbative approach based on the high-order calculation of the pathlength of photons inside the lesion was applied to estimate differences between lesion and average healthy breast tissue in terms of: i) absorption properties, and ii) concentration of the major tissue constituents (oxy- and deoxy-hemoglobin, water, lipid and collagen). The absorption difference a between lesion and healthy tissue is significantly different for malignant vs. benign lesions at all wavelengths. Logistic regression fitted to the absorption data identifies 975 nm as the key wavelength to discriminate malignant from benign lesions. When the difference in tissue composition between lesion and healthy tissue is considered, malignant lesions are characterized by significantly higher collagen content than benign lesions. Also the best model for the discrimination of malignant lesions obtained applying regression logistic to tissue composition is based only on collagen
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